Prior known mechanically steered antennas for use in mobile satellite communication systems have employed rotary connectors for coupling the signal supply cable from a radio receiver/transmitter communication system to the antenna. Alternatively, a loop of cable for the same purpose is employed. However, rotary connectors are expensive and tend to generate electrical noise in the radio frequency band while in use. Although rotary connectors subject to the above-discussed shortcomings are capable of full 360 degree rotation in azimuth, coiled cable loops allow an antenna to rotate only a few times before the direction of the rotation of the antenna must be reversed to untangle the coiled loop. Cable loops also take up more room than rotary couplers and in addition tend to become noisy after the cable has been flexed and unflexed many times.
In addition to the above disadvantage, prior steerable antennas for tracking satellites on small mobile units usually require that the entire antenna system, including the antenna itself, be enclosed in a radome. This increases the size and mass of the antenna as well as wind resistance since the radome must enclose the total space occupied by the antenna as it rotates throughout all azimuth directions. This results in an antenna system which is bulky, provides considerable wind resistance to vehicles on which such radomes are mounted, and is not pleasing in appearance.
To overcome the above objectionable features of known prior art steerable satellite tracking antennas for use on mobile units such as trucks, vans, cars, boats and the like, the present invention was devised in which a principle purpose of the invention is to eliminate the need for a coiled cable loop or a rotary joint and the need for enclosure of the antenna in a radome as has been done in the past.